A worker outside London's O2 arena on Friday sits below a screen bearing a message about Michael Jackson's death. (Akira Suemori/Associated Press)The day after Michael Jackson's death, some still-mourning fans are wondering whether they'll get refunds for the London concert series the King of Pop was to have started in just two weeks.

Concert promoter and producer AEG Live had been scheduled to host Jackson's 50-concert residency at London's O2 arena beginning July 13.

A statement on AEG Live's website on Friday said "full ticket refund information and procedures will be released early next week" for all ticket holders.

"Fans are advised to hold onto their ticket vouchers/proof of purchase," the statement said.

Billed as the singer's farewell performance, with an estimated cost of $20 million US to stage, the This Is It series quickly sold out after 750,000 fans rushed to snap up tickets.

AEG representatives have said in interviews that Britons purchased about 90 per cent of the concert tickets, while fans from other countries purchased the balance.

Ticketmaster, estimated to have sold more than half of the tickets, released a statement saying the company "is aware of the news relating to Michael Jackson. We have no official information at this stage."

Eric Baker, chief executive of Viagogo, a British online ticket-exchange company, said in a statement that all tickets purchased via his company will be refunded directly, "no forms, no fuss, just refunded. We will be in touch with everyone in due course."

Seatwave, another online ticket agency, sold around three per cent of the seats for the London concert series, and said it would refund all tickets purchased via its website. "This is the biggest cancellation I've ever seen," Seatwave head Joe Cohen told Forbes.

Michael Jackson fans Karen Marcemy and David Vilo stand outside the Lyric Theatre in London, which is showing the musical Thriller, on Friday. (Matt Dunham/Associated Press)According to a spokeswoman for eBay, fans who purchased their tickets from private sellers on the online auction site should first contact the seller to obtain a refund. If the purchase was made with a PayPal account, it is also covered by insurance and a claim must be filed within 45 days.

In London, shocked Jackson fans gathered at the Lyric Theatre — home of a live show based on the album Thriller — and awaited news regarding refunds.

According to Billboard magazine, ticket sales had generated more than $85 million US, with AEG already having spent as much as $30 million on the concerts, for which Jackson had been rehearsing in Los Angeles.

'No issues whatsoever'

AEG Live CEO Rand Phillips said in interviews in May that Jackson had undergone medical screening and that there were "no issues whatsoever."

Jackson's manager, Frank DiLeo, told the Los Angeles Times that as late as Wednesday night, Jackson appeared happy with the progress of rehearsals and the prospect of the London concerts.

"He just told me how happy he was and that things were finally working out the way he wanted," DiLeo said.

Choreographer Kenny Ortega, who worked on Dangerous and other Jackson music videos, and also directed the High School Musical films, had been directing the famed entertainer for the This Is It shows.

"We had a 25-year friendship. This is all too much to comprehend," Ortega said in a statement. "This was the world's greatest performer, and the world will miss him."

With files from The Associated Press